The present invention relates generally to attitude control of orbital satellites. More specifically, but without limitation thereto, the present invention relates to avoiding thermal shock to a satellite solar panel as it enters and exits the earth""s shadow.
Sudden changes in the shape of materials in space may occur during the rapid transitions between exposure to sunlight and shade. The temperature changes resulting from these transitions are thermal shocks that may cause large solar panels to snap or buckle, imparting a torque to the satellite. This torque may disturb the attitude of the satellite and affect critical aiming of its beam antennas. As higher power requirements demand solar panels with increasing surface area and mass, the torque impulses from thermal shock become more severe, while at the same time tighter beam antenna pointing requirements become more sensitive to the resulting antenna misalignment.
Feed forward or open loop attitude control methods based on analysis and orbit data may exacerbate the problem of thermal shock unless the timing of the attitude disturbance can be predicted with high accuracy. Because of variation in the sun""s declination, ephemeris error, manufacturing tolerances, material quality, and design variability, it has been difficult to predict the timing well enough to use feed forward or open loop techniques advantageously.
The present invention advantageously addresses the needs above as well as other needs by providing a method and apparatus for avoiding thermal shock to a satellite solar wing.
In one embodiment, the invention may be characterized as a solar wing control system for avoiding thermal shock to a solar wing that includes an eclipse exit slew profile generator having an eclipse exit slew rate output for rotating the solar wing from an eclipse exit angle to a solar power generation angle to control solar wing heating rate.
In another embodiment, the invention may be characterized as a method for avoiding thermal shock to a solar wing by rotating the solar wing from an eclipse exit angle to a solar power generation angle to control solar wing heating rate.
The features and advantages summarized above in addition to other aspects of the invention will become more apparent from the description, presented in conjunction with the following drawings.